A significant proportion of teens involved in the juvenile justice system abuse substances. Multiple drug use increases the likelihood of remaining a youth involved in crime. Many teens involved in crime use alcohol or drugs prior to the commission of delinquent acts. A substantial number of delinquent youths who are offered treatment are unmotivated for intervention. The objective of this research is to investigate ways to enhance motivation for treatment and effectively reduce substance abuse among juvenile offenders. Motivational intervention (MI) as preparation for residential treatment and for persons (including teens) with little motivation to change has been effective in reducing substance abuse. Thus, MI designed for delinquent youths who are required to attend substance abuse treatment may prove efficacious. In this proposed randomized trial, a one-way design (MI + Standard Care [SC] vs. Attention Control [AC] + SC) will be used to determine whether MI enhances subsequent treatment participation and reduces substance-related problems post discharge in substance using, delinquent youths. Teens will also receive a booster session of MI or AC prior to discharge. SC includes skills training and psycho-educational components; AC provides relaxation training. Participants will be followed at 3 months post discharge. Primary outcome variables include alcohol and marijuana use, as well as related behaviors (illegal activity, sex or injures while drunk or high). It is hypothesized that in comparison to teens receiving AC, youths receiving MI will participate more (by therapist and teen ratings) in SC and will show the lowest levels of heavy substance use and related problems after discharge. It is hypothesized that effects found post discharge will be mediated by stage of change, drug effect expectancies, self-efficacy and treatment participation. This study will extend previous research by evaluating the use of MI with ethnically diverse substance abusing teens in a correctional facility, and by expanding outcome measures to include alcohol and marijuana-related risk behavior (such as injuries and illegal activity when drunk or high) in this population. The development of effective interventions for substance using juvenile offenders has the potential to reduce substance abuse and crime in this population.